This invention relates to a thermoformed dispensing container that has a positive seal formed memory valve. This invention further relates to a container having a valve comprised of a channel wherein a suckback can be designed into the valve whereby the dispensing container can substantially retain its original shape.
The present invention is directed to the problem of sealing a container once it has been opened and a portion of the contents removed. These containers usually are opened by removing a part of the container to expose an opening. This usually is a tear away tab. Upon putting pressure on the main body of the container, some of the contents can be dispensed. The remainder of the contents stay in the container. The present invention provides a positive sealing valve arrangement so that after each dispensing the contents are positively sealed within the body of the container. The valve is comprised of a channel with a unique formed memory valve disposed in the channel.
The thermoformed container in one embodiment also can have a suckback feature. By suckback is meant that after a dispensing of some of the product from the container, air is drawn in through the valve to replace the product that has been dispensed. In this way the container substantially retains it original shape. The degree of suckback will be determined by the rheology of the material being dispensed, the structure of the valve and the resiliency of the material of the container.
Various types of valves for thermoformed containers are known. Such containers with flat channel valves are disclosed in U.S. Pat. No. 3,184,121; U.S. Pat. No. 4,491,157 and U.S. Pat. No. 5,529,224. In FIG. 6 of U.S. Pat. No. 3,184,121 there is shown two parallel flat sheets of material that are opened to dispense a product by a force on the walls of the container. A related valve mechanism is shown in U.S. Pat. No. 4,917,567. FIG. 5C of this patent shows the valve in a dispensing condition. U.S. Pat. No. 5,529,224 is directed to various embodiments of flat channel valves in combination with a thermoformed container. Flat channel valves are well known in the art. However, they have a disadvantage in that they do not provide a positive sealing. Further, the thickness and other characteristics of the thermoformed container materials must be closely designed to provide a reasonably good seal. An improvement over such channel valves is disclosed in U.S. Pat. No. 5,839,609 which discloses a ridge valve arrangement for a channel valve.
Another type of seal is a deformable seal. This is described in U.S. Pat. No. 3,635,376, U.S. Pat. No. 4,928,852 and to an extent in U.S. Pat. No. 5,529,224, FIGS. 26 through 30. In this type of valve one sheet, usually the upper sheet, is designed to have a sufficient integrity to be moved manually from an open position to a closed position. The top sheet is moved manually from an upper position where the valve is open to a lower position where the valve is closed. The manual opening and closing of this type of valve is more clearly shown in FIG. 7 of U.S. Pat. No. 4,928,852.
U.S. Pat. No. 5,839,609 discloses a thermoformed container with a ridge valve. This is a type of a flat channel valve with the integrity of the seal enhanced with depressions on either side of the ridge structure so that the top wall can be drawn downward into a better contact with the ridge by the elasticity of the upper sheet of plastic and the surface tension of the substance being dispensed which is contained in the depressions on either side of the ridge.
Despite the efforts of the inventors of the valve mechanisms of these patents, there has not been achieved a simple, automatic, positive sealing valve for a container. The valves that require manual manipulation require a person to remember to seal the container, while flat channel valves are not positive sealing. A ridge valve provides good sealing but it has a complex structure and is in part a flat channel valve with some of the same shortcomings.
Containers for the storing and dispensing of relatively small volumes of flowable substances can be made inexpensively by thermoforming. However, a problem in the use of containers for other than single dose use is a valve or closure to positively cut off the flow of the flowable substance after a dispensing. Further, in order to avoid inadvertent dispensing the effort to dispense must be one that would not be encountered in the norm al handling of the container. However, the dispensing effort cannot be such as to make it difficult for people with lower hand strength to dispense product from the container. The present container is comprised of a body portion and a valve section. The container is sealed substantially around or periphery. The body portion is comprised of a chamber of essentially any shape with an outlet channel that contains a valve for the dispensing of amounts of a flowable substance. The end of the channel can be sealed by a tear-off tab or an equivalent structure that can be removed to open the outlet channel.
The valve portion is comprised of the channel having a top wall and a bottom wall. The channel can be of essentially any shape and usually will be of a circular or elliptical shape. However it can be polygonal in shape having two, three or more sides. If the channel is circular the upper 180xc2x0 section will comprise a top wall and the lower 180xc2x0 section will comprise the bottom wall. This likewise will apply to an elliptical shape where the wall above the major axis will comprise a top wall and below the major axis a bottom wall. Further, in a dispensing channel at a point a set distance from the chamber which holds the substance to be dispensed, either the top or bottom wall will be shaped to be biased in a position to be in close contact with the other wall by being depressed against the other wall during or after the forming of the container. This results in a formed memory of the walls of the valve. By formed memory is meant that the wall that is placed into contact with other walls will have a memory of the shape into which it ha s been formed. When displaced from this shape into which it has been formed by an applied force, such as that caused by a dispensing, the displaced wall will rapidly regain its former shape upon the removal of the applied force. This is the result of the formed memory.
The flowable substance is dispensed from the container by pressing the walls of the chamber together to decrease the volume of the chamber. This forces the flowable substance from the chamber into the channel which comprises the valve. At a given force the valve opens by one channel wall or walls being displaced out of contact with other channel wall or walls. Upon the removal of the force on the chamber, the channel walls again come into intimate contact as a result of the formed memory of one or more of the channel walls and the dispensing of the flowable substance stops.
The containers also can be designed to have a suckback feature. In this way the container will retain its shape after each dispensing. The amount of product will be replaced by air that is drawn into the container part of the container through the valve. The rheology of the product will determine the structure of the container valve and container product chamber in order to get a sufficient suckback. In addition there should be a narrowed region prior to the valve to provide a venturi through which the product and air must flow.
This container with this valve can be used to dispense liquids, gels, lotions, oils, pastes and essentially any flowable substance. The structure of the container can be modified for the needs of a particular substance or the environment in which the container is to be used.
A preferred container is a thermoformed container. The present valve with a formed memory will be at one end of the container. The valve usually will be formed at the same time as the container and will be in the form of a unitary section with the container. The valve is very useful on thermoformed containers since it is an effective way to make a thermoformed container a multidose container. Without an effective valve arrangement thermoformed containers can only be used as single dose containers.
Although thermoformed containers are the preferred containers, containers molded by other techniques can also effectively use the present valve. In these other embodiments the containers and the formed memory valves can be molded as one piece or molded in two or more pieces and assembled.